This is a very generic error and as much as I would like to give you a perfect answer, I've never come up with one. The most likely cause are write delays introduced by your system. Either a device driver is not right or due to compatibility issues, the USB bus is reverting to 1.1 instead of using 2.0, which in turn causes data to be lost because the transfers are too slow. I would simply try to plug the disk into a different port and try again. e.g. if it's plugged to a front port, the described scenario may occur because the internal cables to those ports are slightly too long, but if you plug it in from behind, it may work perfectly. And of course use a good USB cable. If your disk uses poweer stabilization by ways of providing a second USB plug just for voltage, use it, even if it may normally not be necessary. This may stabilize things and even allow the disk to rev up a little.

Well, if your FireWire bus suffers similar problems, it might not be any different. Hard to tell from a distance. Before spending a lot of money on something that might potentially not work, either, I'd try to debug the issue a bit. A simple way of testing stability would be to copy a very large file (bigger than 4GB) to and from the disk several times as well as do the same with a directory full of hundreds of very small files. if either of the processes goes extremely slow, stutters inebtween or throws errors, it would reveal more about the state of your drive and USB connection. E.g. very slow large file transfer would be a clear sign of the external drive being heavily fragmented, where slow access on small files could indicate file table/ data integrity problems. Anyway, these days one would probably rather use eSATA drives for externals, so ideally, buy a combo drive that supports USB, FireWire and eSATA....